Oil-soluble disazo dyes and their use in color-photographic recording materials for the silver dye bleach process

ABSTRACT

Compounds of the formula ##STR1## in which X 1  is hydrogen, alkyl, alkoxy, --NL 1  COM 1 , in which L 1  is hydrogen or alkyl and M 1  is alkyl or alkoxy, or is --NL 1  P(O)(OG 1 ) 2 , in which G 1  is alkyl, or is alkylsulfonamide or hydroxyl, Y 1  is hydrogen, alkyl, alkoxy, carbalkoxy, N-alkyl-substituted or N,N-dialkyl-substituted amino or --NL 2  COM 2 , in which L 2  is hydrogen or alkyl and M 2  is alkyl or alkoxy, Z 1  is hydrogen, alkyl, alkoxy, --NL 2  COM 3 , in which M 3  is alkyl, or is carbalkoxy or halogen or represents those atoms which are required to form a ring with Y 1 , W 1   is hydrogen, alkyl or alkoxy, R 1  and R 2  independently of one another are hydrogen, halogen, cyano, nitro or --SO 2  U 3 , in which U 3  is alkyl or phenyl, R 3  is hydrogen or alkyl or, if R 4  is a direct chemical bond, the two radicals R 3  together are a link member and R 4  is a direct chemical bond or a link member, and at least two of the substituents W 1 , X 1 , Y 1  and Z 1  are other than hydrogen. The compounds can be used with particular advantage as image dyes, for example in photographic materials for the silver dye bleach process. Color images with excellent color reproduction are obtained.

The present invention relates to new, oil-soluble disazo dyes and their use in colour-photographic recording materials for the silver dye bleach process.

The use of water-soluble polyazo dyes or azoxy dyes for the silver dye bleach process is known (A. Meyer, J. Phot. Sci. 13, (1965), 90; Research Disclosure 17643/VII A, December 1978). On the one hand, the use of azo dyes of this type has advantages inasmuch as easy and homogeneous dyeing of the hydrophilic, colloidal binders of a photographic layer, in particular gelatine, is possible. Moreover, during the processing of exposed silver dye bleach materials, water-soluble scission products or azo dyes, which can readily be washed out, are formed in the exposed areas. However, amongst the disadvantages which arise when water-soluble azo dyes are used, the tendency of these dyes to diffuse within and between photographic layers should be mentioned in particular. To overcome this disadvantage, the use of reactive dyes has been proposed in the past. However, this entailed an unduly large effect on the rheological, chemical and mechanical properties of the photographic layer to be prepared. The use of higher-molecular water-soluble azo dyes also did not give a completely satisfactory result. Although the diffusion resistance is increased in this way, the tendency of such dyes to form micelles by aggregation represents a further disadvantage which significantly interferes with the colour density of the photographic image.

Swiss Patent Specification No. 600,385 now describes a silver dye bleach process in which water-insoluble azo dyes with masked auxochromes are dispersed in gelatine. These dyes, however, are bleached only slowly and sometimes incompletely. Moreover, the regeneration of the desired image dye requires a special treatment in a strongly alkaline medium. Other water-insoluble azo dyes which had been incorporated in silver dye bleach materials are accessible only with difficulty and their stability under changes in the pH value and under the action of light is unduly low (U.S. Pat. No. 3,544,326; Research Disclosure 14,983, September 1976).

It is thus the object of the present invention to provide new disazo dyes for use in colour-photographic recording materials for the silver dye bleach process, which dyes can readily be incorporated into the layers of the recording materials and which, due to their fastness properties, lead to a material which gives images of improved quality.

Oil-soluble disazo dyes for use in photographic layers of silver dye bleach materials have now been found, which impart the desired properties to the recording material and give photographic images of high quality.

The present invention therefore relates to compounds of the formula ##STR2## in which X₁ is hydrogen, alkyl or alkoxy each having 1 to 6 carbon atoms, or --NL₁ COM₁, in which L₁ is hydrogen or alkyl having 1 to 4 carbon atoms and M₁ is alkyl or alkoxy, which have 1 to 20 carbon atoms and are unsubstituted or substituted by carbalkoxy having 2 to 5 carbon atoms or by alkoxy having 1 to 4 carbon atoms, or X₁ is --NL₁ P(O)(OG₁)₂, in which L₁ is as defined above and G₁ is alkyl having 1 to 12 carbon atoms, or X₁ is alkylsulfonamide having 1 to 20 carbon atoms or hydroxyl, Y₁ is hydrogen, alkyl having 1 to 6 carbon atoms, alkoxy having 1 to 12 carbon atoms or --(OC₂ H₄)_(n1) --OU₁, in which U₁ is hydrogen, alkyl having 1 to 6 carbon atoms or phenyl and n₁ is 1, 2 or 3, or Y₁ is N-alkyl-substituted or N,N-dialkyl-substituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by electronegative groups, or Y₁ is --NL₂ COM₂, in which L₂ is hydrogen or alkyl having 1 to 6 carbon atoms and M₂ is alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 4 carbon atoms or --O--C₂ H₄ O)_(n1) --U₂, in which U₂ is alkyl having 1 to 8 carbon atoms and n₁ is as defined above, Z₁ is hydrogen, alkyl having 1 to 12 carbon atoms or --CH₂ CO₂ R₅, in which R₅ is alkyl having 1 to 8 carbon atoms or --(C₂ H₄ O)_(n1) --U₁, in which U₁ and n₁ are as defined above, or Z₁ is alkoxy having 1 to 8 carbon atoms or --(OC₂ H₄)_(n1) --OU₁ in which U₁ and n₁ are as defined above, or Z₁ is --NL₂ COM₃, in which L₂ is as defined above and M₃ is alkyl having 1 to 18 carbon atoms, or Z₁ is carbalkoxy having 2 to 19 carbon atoms or --CO(OC₂ H₄)_(n1) --OU₁, in which U₁ and n₁ are as defined above, or Z₁ is halogen or represents those atoms which are required in order to form, together with Y₁, a 5-membered or 6-membered, saturated or unsaturated ring which is unsubstituted or substituted by alkyl having 1 to 4 carbon atoms, W₁ is hydrogen, alkyl or alkoxy each having 1 to 4 carbon atoms, R₁ and R₂ independently of one another are hydrogen, halogen, cyano, nitro or --SO₂ U₃, in which U₃ is alkyl having 1 to 6 carbon atoms, which is unsubstituted or substituted by hydroxyl or alkoxy having 1 to 6 carbon atoms, or is phenyl, R₄ is a direct chemical bond or a link member of the formula --O--, --CO--, --SO₂ --, --(CH₂)_(m1) --, in which m₁ is an integer from 1 to 8, or --CH═CH--, and R₃ is hydrogen or alkyl having 1 to 12 carbon atoms or, if R₄ is a direct chemical bond, the two radicals R₃ together can be a link member of the formula --CH₂ -- or --CO--, and at least two of the substituents W₁, X₁, Y₁ and Z₁ are other than hydrogen.

The invention also relates to the use of the compounds as image dyes in colour-photographic recording materials for the silver dye bleach process.

Moreover, the invention relates to a colour-photographic recording material for the silver dye bleach process, which material contains these compounds, to a process for the preparation of the compounds, and to the photographic images produced with the material.

The substituent X₁ in formula (1) is hydrogen, hydroxyl or alkyl having 1 to 6 carbon atoms. The alkyl radicals can be straight-chain or branched. Examples are methyl, ethyl, propyl, i-propyl, butyl, 3-methylpropyl, 1-methylpropyl, tert.-butyl, pentyl, 1,1-dimethylpropyl, 3,3-dimethylpropyl, hexyl, 4,4-dimethylbutyl and 1,3-dimethylbutyl.

Methyl and ethyl, in particular methyl, are the preferred alkyl radicals.

Hydroxyl is a very suitable radical.

An alkoxy radical X₁, having 1 to 6 carbon atoms, can be analogous to the alkyl radicals mentioned.

Methoxy and ethoxy, in particular methoxy, are the preferred alkoxy radicals.

X₁ can also be a radical of the formula --NL₁ COM₁ in which L₁ is hydrogen or alkyl having 1 to 4 carbon atoms, for example methyl, ethyl, propyl, i-propyl, butyl, 1-methylpropyl, 3-methylbutyl or tert.-butyl. Methyl, ethyl and propyl are preferred alkyl radicals, methyl being especially suitable. Hydrogen is also a very suitable radical. M₁ is alkyl having 1 to 20 carbon atoms, and these alkyl radicals can be straight-chain or branched. Examples of such alkyl radicals are: methyl, ethyl, propyl, i-propyl, butyl, 1-methylpropyl, 3-methylpropyl, tert.-butyl, pentyl, 1,1-dimethylpropyl, 3,3-dimethylpropyl, hexyl, 1,1,3,3-tetramethylbutyl, 1-methylethylpentyl, 1-methylpentyl, neopentyl, 1-, 2- or 3-methylhexyl, heptyl, n-octyl, tert.-octyl, 2-ethylhexyl, n-nonyl, isononyl, tert.-nonyl, decyl tert.-decyl; undecyl, dodecyl, tetradecyl, hexadecyl, octadecyl or eicosyl as well as the respective isomers.

Alkyl radicals having 1 to 16 carbon atoms are preferred. Particularly suitable alkyl radicals having 1 to 8 carbon atoms. All the alkyl radicals mentioned can be substituted by carbalkoxy having 2 to 5 carbon atoms or by alkoxy having 1 to 4 carbon atoms, and the alkoxy moiety as well as the alkoxy radicals can be straight-chain or branched. M₁ can also be alkoxy having 1 to 20 carbon atoms. The alkoxy radicals can be analogous to the alkyl radicals mentioned, and they can be further substituted by carbalkoxy having 2 to 5 carbon atoms or by alkoxy having 1 to 4 carbon atoms.

X₁ can also be a radical of the formula --NL₁ P(O)(OG₁)₂, in which L₁ is as defined above. G₁ is alkyl having 1 to 12, in particular 1 to 8, carbon atoms. Particularly suitable alkyl radicals contain 1 to 4 carbon atoms. Examples of possible alkyl radicals are given in the definitions of M₁.

In an alkylsulfonamide radical X₁, the alkyl moiety contains 1 to 20, in particular 1 to 16, carbon atoms. Preferably, the alkyl moiety has 1 to 12 carbon atoms. Examples of possible alkyl radicals are given in the definitions of M₁.

Y₁ is hydrogen or alkyl having 1 to 6, in particular 1 to 4, carbon atoms. Examples of suitable alkyl radicals are given in the definitions of X₁.

Y₁ can also be alkoxy having 1 to 12, in particular 1 to 8, carbon atoms. Possible alkoxy radicals are listed in the definitions of M₁.

In a radical Y₁ of the formula --(OC₂ H₄)_(n1) --OU₁, n₁ is 1, 2 or 3, especially 1 or 2. U₁ is hydrogen, phenyl or alkyl having 1 to 6 carbon atoms. Examples of possible alkyl radicals are listed in the definitions of X₁.

In N-alkylsubstituted or N,N-dialkylsubstituted amino radicals Y₁, the alkyl radicals each contain 1 to 8 carbon atoms. Suitable alkyl radicals are those listed for X₁ and also heptyl, octyl and tert.-octyl. These alkyl radicals can be substituted by electronegative groups, for example methoxy, ethoxy, acetoxy, hydroxyl or cyano. Methoxy, ethoxy, hydroxyl and cyano are the preferred electronegative substituents. Methoxy and cyano are very particularly suitable.

Furthermore, Y₁ can be a radical of the formula --NL₂ COM₂, in which L₂ is hydrogen or alkyl having 1 to 6 carbon atoms. Examples of suitable alkyl radicals are listed in the definitions of X₁. M₂ is alkyl having 1 to 12, in particular 1 to 6, carbon atoms. The definitions of M₁ contain suitable examples of possible alkyl radicals. M₂ can also be alkoxy having 1 to 4 carbon atoms, and this can be, for example, methoxy, ethoxy, propoxy, butoxy, tert.-butoxy, 1-methylpropoxy or 3-methylpropoxy. In an M₂ radical --O--C₂ H₄ O)_(n1) --U₂, n₁ is as defined above. U₂ is alkyl having 1 to 8, in particular 1 to 4, carbon atoms. Suitable alkyl radicals are listed in the definitions of M₁. Methyl is a preferred alkyl radical.

Z₁ is hydrogen or alkyl having 1 to 12, in particular 1 to 8, carbon atoms. The definition of M₁ contains examples of suitable alkyl radicals.

Furthermore, Z₁ can be a radical of the formula --CH₂ CO₂ R₅, in which R₅ is alkyl having 1 to 8, in particular 1 to 4, carbon atoms. Examples are given in the definitions of M₁. R₅ can also be --(C₂ H₄ O)_(n1) --U₁, in which U₁ and n₁ are as defined above.

An alkoxy radical Z₁ contains 1 to 8, in particular 1 to 5, carbon atoms. Suitable alkoxy radicals can be found in the definitions of M₁.

Z₁ can also be a radical of the formula --(OC₂ H₄)_(n1) --OU₁, in which U₁ and n₁ are as defined above.

Z₁ can be a radical of the formula --NL₂ COM₃, in which L₂ is as defined above and M₃ is alkyl having 1 to 18, in particular 1 to 12, carbon atoms. Particularly suitable alkyl radicals contain 1 to 8 carbon atoms. The alkyl radicals can be those mentioned in the definitions of M₁.

Z₁ can be carbalkoxy having 2 to 19, in particular 2 to 12, carbon atoms, examples of the alkyl or alkoxy radicals being given in the definitions of M₁. Carbalkoxy having 2 to 5 carbon atoms is particularly preferred.

In a Z₁ radical --CO(OC₂ H₄ 9_(n1) --OU₁, U₁ and n₁ are as defined above.

A halogen radical Z₁ is, for example, fluorine, chlorine or bromine, chlorine and bromine being preferred.

Z₁ can form, together with Y₁ and the carbon atoms to which Z₁ and Y₁ are bonded, 5-membered to 6-membered ring which can be saturated or unsaturated. This ring can be substituted by alkyl substituents having 1 to 4 carbon atoms, in particular methyl.

W₁ is hydrogen, or alkyl or alkoxy each having 1 to 4 carbon atoms, for example methyl, ethyl, propyl, butyl, and tert.-butyl or methoxy, ethoxy, propoxy, butoxy and tert.-butoxy. Methyl and methoxy are particularly suitable.

R₁ and R₂ independently of one another are hydrogen, halogen, for example chlorine or bromine, cyano, nitro or a radical of the formula --SO₂ U₃. U₃ is alkyl having 1 to 6, in particular 1 to 4, carbon atoms. Suitable examples are listed in the definition of X₁. Methyl is particularly suitable. The alkyl radicals can be substituted further by hydroxyl or alkoxy having 1 to 6 carbon atoms. Possible alkoxy radicals are described in the definition of X₁. Methoxy is particularly preferred. U₃ can also be phenyl.

R₃ is hydrogen or alkyl having 1 to 12, in particular 1 to 8, carbon atoms. Alkyl radicals having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, are particularly suitable. Useful alkyl radicals are methyl and ethyl. Further examples of suitable alkyl radicals are given in the definitions of M₁. The two radicals R₃ can form a link member of the formula --CH₂ -- or --CO--, if R₄ is a direct chemical bond.

R₄ is a direct chemical bond or a link member of the formula --O--, --CO--, --SO₂ --, --(CH₂)_(m1) --, in which m₁ is an integer from 1 to 8, in particular 1 to 6, or is --CH═CH--.

--CO--, --SO₂ --, --CH₂ -- and --CH═CH-- are particularly suitable radicals R₄. The preferred link members are --CO-- and --SO₂ --.

At least two of the substituents X₁, Y₁, Z₁ and W₁ must be other than hydrogen.

Amongst the oil-soluble disazo dyes of the formula (1), those are preferred in which X₁ is alkyl or alkoxy each having 1 to 6 carbon atoms or --NL₁ COM₁, in which L₁ is hydrogen or alkyl having 1 to 4 carbon atoms and M₁ is alkyl or alkoxy, which have 1 to 20 carbon atoms and are unsubstituted or substituted by carbalkoxy having 2 to 5 carbon atoms or by alkoxy having 1 to 4 carbon atoms, or X₁ is --NL₁ P(O)(OG₁)₂, in which L₁ is as defined above and G₁ is alkyl having 1 to 12 carbon atoms, or X₁ is alkylsulfonamide having 1 to 20 carbon atoms or hydroxyl, Z₁ is alkyl having 1 to 12 carbon atoms or --CH₂ CO₂ R₅, in which R₅ is alkyl having 1 to 8 carbon atoms or --(C₂ H₄ O)_(n1) --U₁ in which U₁ and n₁ are as defined above, or Z₁ is alkoxy having 1 to 8 carbon atoms or --(OC₂ H₄)_(n1) --OU₁, in which U₁ and n₁ are as defined above, or Z₁ is --NL₂ COM₃, in which L₂ is as defined above and M₃ is alkyl having 1 to 18 carbon atoms, or Z₁ is carboalkoxy having 2 to 19 carbon atoms or --CO(OC₂ H₄)_(n1) --OU₁, in which U₁ and n₁ are as defined above, or Z₁ is halogen or represents those atoms which are required in order to form, together with Y₁, a 5-membered or 6-membered, saturated or unsaturated ring which is unsubstituted or substituted by alkyl having 1 to 4 carbon atoms, and Y₁, W₁, R₁, R₃ and R₄ are as defined above, at least one of the substituents R₁, R₂ and R₃ being other than hydrogen, if R₄ is a direct chemical bond.

Preferred oil-soluble disazo dyes are those of the formula ##STR3## in which X₂ is methoxy or --NL₁₁ COM₁₁, in which L₁₁ is hydrogen or methyl and M₁₁ is alkyl or alkoxy, which have 1 to 16 carbon atoms and are unsubstituted or substituted by carbalkoxy having 2 to 5 carbon atoms or by ethoxy or methoxy, or X₂ is --NL₁₁ P(O)(OG₁₁)₂, in which L₁₁ is as defined above and G₁₁ is alkyl having 1 to 8 carbon atoms, or X₂ is alkylsulfonamide having 1 to 16 carbon atoms or hydroxyl, Y₂ is hydrogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 12 carbon atoms or --OC₂ H₄)_(n1) OU₁₁, in which U₁₁ is hydrogen, alkyl having 1 to 4 carbon atoms or phenyl and n₁ is as defined above, or Y₂ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy, acetoxy, hydroxyl or cyano, or Y₂ is --NL₂₁ COM₂₁, in which L₂₁ is hydrogen or alkyl having 1 to 4 carbon atoms and n₁ is as defined above, Z₂ is hydrogen, alkyl having 1 to 8 carbon atoms or --CH₂ CO₂ R₅₁, in which R₅₁ is alkyl having 1 to 8 carbon atoms or --C₂ H₄ O)_(n1) --U₁₁, in which U₁₁ and n₁ are as defined above, or Z₂ is alkoxy having 1 to 8 carbon atoms, --(OC₂ H₄)_(n1) --OU₁₁, in which U₁₁ and n₁ are as defined above, or --NL₂₁ COM₃₁, in which L₂₁ is as defined above and M₃₁ is alkyl having 1 to 12 carbon atoms, or Z₂ is carbalkoxy having 2 to 12 carbon atoms or --CO(OC₂ H₄)_(n1) --OU₁₁, in which U₁₁ and n₁ are as defined above, or Z₂ is chlorine or bromine or represents those atoms which are required in order to form, together with Y₂, an unsubstituted or methyl-substituted, 6-membered, saturated ring which may contain 1 or 2 hetero-atoms, W₂ is hydrogen or methyl, R₁₁ and R₂₁ independently of one another are hydrogen, chlorine, bromine, cyano, nitro or --SO₂ U₃₁, in which U₃₁ is alkyl having 1 to 4 carbon atoms, which is unsubstituted or substituted by hydroxyl or methoxy, or is phenyl, R₄₁ is a direct chemical bond or a link member of the formula --O--, --CO--, --SO₂ --, --(CH₂)_(m2) --, in which m₂ is an integer from 1 to 6, or --CH═CH--, and R₃₁ is hydrogen or alkyl having 1 to 8 carbon atoms or, if R₄₁ is a direct chemical bond, the two radicals R₃₁ together can be a link member of the formula --CH₂ -- or --CO--, and at least one of the substituents Y₂, Z₂ and W₂ is other than hydrogen.

Suitable compounds of the formula (2) are those of the formula ##STR4## in which X₃ is methoxy or --NHCOM₁₂, in which M₁₂ is alkyl having 1 to 16 carbon atoms, which is unsubstituted or substituted by carbalkoxy having 2 to 5 carbon atoms or by methoxy or ethoxy, or X₃ is --NHP(O)(OG₁₂)₂, in which G₁₂ is alkyl having 1 to 4 carbon atoms, or X₃ is alkylsulfonamide having 1 to 12 carbon atoms or hydroxyl, Y₃ is hydrogen, alkoxy having 1 to 12 carbon atoms or --OC₂ H₄)_(n2) --OU₁₂, in which U₁₂ is hydrogen or alkyl having 1 to 4 carbon atoms and n₂ is 1 or 2, or Y₃ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy, hydroxyl or cyano, or Y₃ is --NHCOM₂₂ , in which M₂₂ is alkyl having 1 to 4 carbon atoms, methoxy or --O--(C₂ H₄ O)_(n2) --CH₃, in which n₂ is as defined above, Z₃ is hydrogen, alkyl having 1 to 8 carbon atoms or --CH₂ CO₂ R₅₂, in which R₅₂ is alkyl having 1 to 8 carbon atoms or --(C₂ H₄ O)_(n2) --U₁₂, in which U₁₂ and n₂ are as defined above, or Z₃ is alkoxy having 1 to 8 carbon atoms or --(OC₂ H₄)_(n2) --OU₁₂, in which U₁₂ and n₂ are as defined above, or is --NL₂₁ COM₃₂, in which L₂₁ is as defined above and M₃₂ is alkyl having 1 to 8 carbon atoms, or Z₃ is carbalkoxy having 2 to 5 carbon atoms or --CO(OC₂ H₄)_(n2) --OU₁₁, in which U₁₁ and n₂ are as defined above, and W₂, R₁₁, R₂₁, R₃₁ and R₄₁ are as defined above, and at least one of the substituents Y₃, Z₃ and W₂ is other than hydrogen.

Those compounds are also preferred which are of the formula ##STR5## in which R₁₂ and R₂₂ independently of one another are hydrogen, chlorine, bromine, cyano, nitro or methylsulfone, R₄₂ is a direct chemical bond or a link member of the formula --O--, --CO--, --SO₂ --, --(CH₂)_(m2) --, in which m₂ is as defined above, or --CH═CH--, R₃₂ is hydrogen or alkyl having 1 to 4 carbon atoms or, if R₄₂ is a direct chemical bond, the two radicals R₃₂ can be a link member of the formula --CH₂ -- or --CO--, and X₃, Y₃, Z₃ and W₂ is other than hydrogen.

Of interest are compounds of the formula ##STR6## in which X₄ is --NHCOM₁₂ or --NHP(O)(OG₁₂)₂, in which M₁₂ and G₁₂ are as defined above, or is hydroxyl, Z₄ is hydrogen, alkyl or alkoxy having 1 to 8 carbon atoms or --CH₂ CO₂ R₅₃, in which R₅₃ is alkyl having 1 to 4 carbon atoms, --(C₂ H₄ O)₂ --CH₃ or --C₂ H₄ O--CH₃, or Z₄ is --OC₂ H₄)_(n2) --OU₁₂ or --NL₂₁ COM₃₂, in which U₁₂, n₂, L₂₁ and M₃₂ are as defined above, R₃₃ is hydrogen or methyl or, if R₄₂ is a direct chemical bond, the two radicals R₃₃ together can be a link member of the formula --CH₂ -- or --CO--, and W₂, Y₃, R₁₂, R₂₂ and R₄₂ are as defined above, and at least one of the substituents W₂, Y₃ and Z₄ is other than hydrogen.

Valuable compounds of the formula (5) are then those of the formula ##STR7## in which X₅ is --NHCOM₁₃, in which M₁₃ is alkyl having 1 to 16 carbon atoms, or --NHP(O)(OG₁₂)₂, in which G₁₂ is as defined above, or is hydroxyl, Y₄ is hydrogen, alkoxy having 1 to 8 carbon atoms or --OC₂ H₄)_(n2) --OU₁₃, in which U₁₃ is methyl or ethyl and n₂ is as defined above, or Y₄ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy, hydroxyl or cyano, Z₅ is hydrogen, alkyl or alkoxy having 1 to 5 carbon atoms or --CH₂ CO₂ R₅₃, in which R₅₃ is as defined above, or Z₅ is --OC₂ H₄)₂ --OCH₃, --OC₂ H₄)₂ --OH, --OC₂ H₄ --OH, --OC₂ H₄ --OCH₃ or --N(CH₃)COM₃₂, in which M₃₂ is as defined above, R₁₃ and R₂₃ independently of one another are hydrogen, chlorine, bromine, cyano, nitro or methylsulfone, R₃₄ is hydrogen or methyl or, if R₄₂ is a direct chemical bond, the two radicals R₃₄ together can be a link member of the formula --CH₂ -- or --CO--, and W₂ and R₄₂ are as defined above, and at least one of the substituents W₂, Y₄ and Z₅ is other than hydrogen.

Particularly interesting compounds of the formula (6) are those of the formula ##STR8## in which X₆ is --NHCOM₁₃ or --NHP(O)(OG₁₂)₂, in which M₁₃ and G₁₂ are as defined above, Y₅ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy or ethoxy, Z₆ is hydrogen, alkoxy having 1 to 5 carbon atoms, --OC₂ H₄)₂ --OCH₃, --OC₂ H₄)₂ --OH, --OC₂ H₄ OCH₃ or --OC₂ H₄ --OH, R₁₄ and R₂₄ independently of one another are hydrogen, chlorine or bromine, R₃₅ is hydrogen or, if R₄₃ is a direct chemical bond, the two radicals R₃₅ together can be a link member of the formula --CH₂ -- or --CO--, and R₄₃ is a direct chemical bond or a link member of the formula --CO--, --SO₂ -- or --CH═CH--.

Particularly valuable compounds of the formula (6) are those of the formula ##STR9## in which Y₆ is N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy or cyano, R₁₅ and R₂₄ independently of one another are cyano, nitro or methylsulfone, R₄₄ is a direct chemical bond or a link member of the formula --CO-- or --SO₂ -- and X₆ and Z₆ are as defined above.

Particularly preferred compounds of the formula (6) are those of the formula ##STR10## in which Y₇ is alkoxy having 1 to 8 carbon atoms or --OC₂ H₄)_(n).sbsb.2 --OU₁₃, in which n₂ and U₁₃ are as defined above, and Z₇ is hydrogen or alkyl having 1 to 5 carbon atoms.

Particularly preferred compounds of the formula (9) are those of the formula ##STR11## in which Z₈ is alkyl having 1 to 3 carbon atoms and Y₇ is as defined above.

Due to their insolubility in water, the dyes can be obtained in a very pure form. They are prepared by conventional methods, for example by tetrazotising an amine of the formula ##STR12## in which R₁, R₂, R₃ and R₄ are as defined above, in the conventional manner in the presence or absence of an organic solvent and coupling the product with a coupling component of the formula ##STR13## in which X₁, Y₁, Z₁ and W₁ are as defined above, in the presence or absence of an organic solvent and in the presence or absence of a base.

When preparing disazo dyes of the formula (1) in which the substituents R₁ and R₂ are cyano, it is advantageous to introduce the cyano group by an exchange reaction with the corresponding halogenated compound.

If R₁ and R₂ in the formula (1) are alkylsulfone, it is likewise possible to prepare the corresponding azo compounds from the halogenated compound by reacting the latter with a suitable sulfinate, optionally in the presence of Cu⁺.

The compounds listed in Table 1 can, for example, be used as the amines of the formula (11).

                  TABLE 1                                                          ______________________________________                                          ##STR14##                                                                     R.sub.1  R.sub.2   R.sub.3                                                                               R.sub.4                                              ______________________________________                                          H       H         H                                                                                      ##STR15##                                            H       H         H                                                                                      ##STR16##                                            H       H         H                                                                                      ##STR17##                                            H       H         H      CH.sub.2                                             H        H         H      CH.sub.2CH.sub.2                                     H        H         H      CH.sub.2 CH.sub.2 CH.sub.2                           H        H         H      CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2                  H        H         H      CHCH                                                  H       H         H                                                                                      ##STR18##                                            H       H         H                                                                                      ##STR19##                                            H       H         H                                                                                      ##STR20##                                            H       H         H                                                                                      ##STR21##                                            H       H         H                                                                                      ##STR22##                                            H       H         H                                                                                      ##STR23##                                            H       H         H                                                                                      ##STR24##                                            Br      Br        H                                                                                      ##STR25##                                            Br      Br        H                                                                                      ##STR26##                                            Br      Br        H                                                                                      ##STR27##                                            Br      Br        H      (CH.sub.2).sub.2                                     Br       Br        CH.sub.3                                                                              (CH.sub.2).sub.2                                     Br       Br        H      (CH.sub.2).sub.3                                     Br       Br        H      (CH.sub.2).sub.4                                      Br      NO.sub.2  H                                                                                      ##STR28##                                            Br      NO.sub.2  H                                                                                      ##STR29##                                            NO.sub.2                                                                               NO.sub.2  H                                                                                      ##STR30##                                            NO.sub.2                                                                               NO.sub.2  H                                                                                      ##STR31##                                            CN      CN        H                                                                                      ##STR32##                                            CN      CN        H                                                                                      ##STR33##                                            Br      Br        H      --                                                   Br       NO.sub.2  H      --                                                   Br       NO.sub.2  H      CH.sub.2                                             Br       NO.sub.2  H      (CH.sub.2).sub.2                                      CN      NO.sub.2  H                                                                                      ##STR34##                                            CN      NO.sub.2  H                                                                                      ##STR35##                                            NO.sub.2                                                                               NO.sub.2  H      --                                                   CN       CN        H      --                                                   CN       CN        H      CH.sub.2                                             CN       CN        H      (CH.sub.2).sub.2                                     CN       NO.sub.2  H      CH.sub.2                                             CN       NO.sub.2  H      (CH.sub.2).sub.2                                      SO.sub.2 CH.sub.3                                                                      NO.sub.2  H                                                                                      ##STR36##                                            SO.sub.2 CH.sub.3                                                                      NO.sub.2  H                                                                                      ##STR37##                                           ______________________________________                                    

Further suitable diamines which can be tetrazotised are of the formulae: ##STR38##

Examples of suitable coupling components are compiled in Table 2.

                                      TABLE 2                                      __________________________________________________________________________      ##STR39##                                   (12)                              X.sub.1          Y.sub.1       Z.sub.1      W.sub.1                            __________________________________________________________________________     OCH.sub.3        N(C.sub.4 H.sub.9).sub.2                                                                     H            H                                  OH               N(C.sub.4 H.sub.9).sub.2                                                                     H            H                                  NHCOCH.sub.3     N(C.sub.4 H.sub.9).sub.2                                                                     H            H                                  NHCOC.sub.2 H.sub.5                                                                             N(C.sub.3 H.sub.7).sub.2                                                                     H            H                                  NHCOC.sub.4 H.sub.9                                                                             N(C.sub.3 H.sub.7).sub.2                                                                     H            H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.2 H.sub.5).sub.2                                                                     H            H                                   NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 ##STR40##    OCH.sub.3    H                                   NHCOCH.sub.3    N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.4 H.sub.9).sub.2                                                                     OCH.sub.3    H                                  NHCOCH.sub.2 CH(CH.sub.3).sub. 2                                                                N(C.sub.6 H.sub.13).sub.2                                                                    H            H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.6 H.sub.13).sub.2                                                                    OCH.sub.3    H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.4 H.sub.9).sub.2                                                                     OCH.sub.3    H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 NHCH(CH.sub.3)CH.sub.2 OCH.sub.3                                                             OCH.sub.3    H                                  NHCO CH(CH.sub.3).sub.2                                                                         NHCH(CH.sub.3)CH.sub.2 OCH.sub.3                                                             OCH.sub.3    H                                  NHCOCH.sub.3     N(C.sub.2 H.sub.5)C.sub.2 H.sub.4 CN                                                         OCH.sub.3    H                                  NHCOC.sub.2 H.sub.5                                                                             N(C.sub.2 H.sub.5).sub.2                                                                     OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  NHCOC.sub.3 H.sub.7                                                                             N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCOCH.sub.3     N(C.sub.4 H.sub.9).sub.2                                                                     OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  NHCOCH(C.sub.2 H.sub.5)C.sub.4 H.sub.9                                                          N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCOCH(C.sub.12 H.sub.25)OC.sub.6 H.sub.4C.sub.5 H.sub.11                                       N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCO.sub.2 C.sub.2 H.sub.4 OCH.sub.2 CH(CH.sub.3).sub.2                                         N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCO.sub.2 C.sub.2 H.sub.4 OCH.sub.2 CH(CH.sub.3).sub.2                                         NHCH(CH.sub.3)CH.sub. 2 OCH.sub.3                                                            OCH.sub.3    H                                  OCH.sub.3        N(C.sub.4 H.sub.9).sub.2                                                                     OCH.sub.3    H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.2 H.sub.5).sub.2                                                                     OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.2 H.sub.5).sub.2                                                                     OC.sub.2 H.sub.5                                                                            H                                  NHCOC.sub.3 H.sub.7                                                                             N(C.sub.2 H.sub.5).sub.2                                                                     OC.sub.4 H.sub.9                                                                            H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 NHC.sub.2 H.sub.4 CN                                                                         H            H                                  NHCOC.sub.11 H.sub.23                                                                           NHC.sub.2 H.sub.4 CN                                                                         H            H                                  NHP(O)(OC.sub.4 H.sub.9).sub.2                                                                  NHC.sub.2 H.sub.4 CN                                                                         H            H                                  NHP(O)(OC.sub.2 H.sub.5).sub.2                                                                  NHCH(CH.sub.3)CH.sub.2 OCH.sub.3                                                             OCH.sub.3    H                                  NHP(O)(OCH.sub.3).sub.2                                                                         N(C.sub.4 H.sub.9).sub.2                                                                     OCH.sub.3    H                                  NHP(O)(OC.sub.2 H.sub.5).sub.2                                                                  N(C.sub.2 H.sub.5).sub.2                                                                     H            H                                  NHP(O)(OC.sub.4 H.sub.9).sub.2                                                                  N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHP(O)(OC.sub.2 H.sub.5).sub.2                                                                  N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHP(O)(OC.sub.2 H.sub.4 OC.sub.2 H.sub.5).sub.2                                                 N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHP(O)(OC.sub.4 H.sub.9 ).sub.2                                                                 NHCH(CH.sub.3)CH.sub.2 OCH.sub.3                                                             OCH.sub.3    H                                  NHP(O)(OC.sub.4 H.sub.9).sub.2                                                                  NHCH(CH.sub.3)CH.sub.2 OCH.sub.3                                                             OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  NHP(O)[OCH.sub.2 CH(CH.sub.3).sub.2 ].sub.2                                                     NHCH(CH.sub.3)CH.sub.2 CH(CH.sub.3).sub.2                                                    OCH.sub.3    H                                  NHP(O)(OC.sub.2 H.sub.5).sub.2                                                                  NHCH(CH.sub.3)CH.sub.2 OCH.sub.3                                                             OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                                 N(C.sub.2 H.sub.5).sub.2                                                                     O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                         H                                  OH               H             C.sub.5 H.sub.11                                                                            H                                  OH               H             C.sub.5 H.sub.11                                                                            C.sub.5 H.sub.11                   OH               H             CO.sub.2 CH.sub.2 CH(CH.sub.3).sub.2                                                        H                                  OH               H             CO.sub.2 (C.sub.2 H.sub.4 O)CH.sub.3                                                        H                                  OH               H             CH.sub.2 CO.sub.2 CH.sub.2 CH(CH.sub.3).sub                                    .2           H                                  OH               H             OCH.sub.2 CH(CH.sub.3).sub.2                                                                H                                  OH               H             O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                         H                                  OH               H             CH.sub.2 CO.sub.2 (C.sub.2 H.sub.4                                             O).sub.2 CH.sub.3                                                                           H                                  OH               H             NHCOCH(C.sub.2 H.sub.5)C.sub.4 H.sub.9                                                      H                                  OH               H             NCH.sub.3 COCH(C.sub.2 H.sub.5)C.sub.4                                         H.sub. 9     H                                  OH               H             O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                         H                                  OH               OH            CO.sub.2 CH.sub.2 CH(CH.sub.3).sub.2                                                        H                                  OH               H             OH           OC.sub.3 H.sub.7                   OH               NHCOCH.sub.3  OCH.sub.3    H                                  OH               NHC.sub.2 H.sub.4 CN                                                                         H            H                                  OH               NHC.sub.2 H.sub.5 CN                                                                         OCH.sub.3    H                                  OH               NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                              OCH.sub.3    H                                  OH               NHCO.sub.2 (C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                OCH.sub.3    H                                  OH               N(C.sub.2 H.sub.4 CN)COCH.sub.3                                                              OCH.sub.3    H                                  OH               OCH.sub.3     OCH.sub.3    H                                  OH               OC.sub.2 H.sub.5                                                                             OC.sub.2 H.sub.5                                                                            H                                  OH               NHC.sub.3 H.sub.7                                                                            H            H                                  OH               NHC.sub.3 H.sub.7                                                                            OCH.sub.3    H                                  OH               N(C.sub.3 H.sub.7).sub.2                                                                     OCH.sub.3    H                                  OH               N(C.sub.4 H.sub.9)COCH.sub.3                                                                 OCH.sub.3    H                                  OH               NHCOCH(C.sub.2 H.sub.5)C.sub.4 H.sub.9                                                       OCH.sub.3    H                                  OH               NHCOCH(C.sub.2 H.sub.5)C.sub.4 H.sub.9                                                       CH.sub.3     H                                  OH               OC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                            CH.sub.3     H                                  OH               O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                          CH.sub.3     H                                  OH               O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3                                                          H            H                                  OH               OCH.sub. 3    NHCOCH.sub.2 CH(CH.sub.3).sub.2                                                             H                                  OH               OCH.sub.2 CH.sub.2 CH(CH.sub.3).sub.2                                                        CH.sub.3     H                                  NHCOC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                            N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  NHCOC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                            N(C.sub.2 H.sub.5).sub.2                                                                     OCH.sub.3    H                                  HNCOC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                            N(C.sub.2 H.sub.5).sub.2                                                                     OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  NHCOC.sub.2 H.sub.4 OC.sub.4 H.sub.9                                                            N(C.sub.2 H.sub.5).sub.2                                                                     OC.sub.2 H.sub.4 OCH.sub.3                                                                  H                                  __________________________________________________________________________

The oil-soluble disazo dyes of the formula (1) can be used for various purposes, but in particular in photographic materials and, in this case, with particular advantage as image dyes for the silver dye bleach process. Accordingly, valuable photographic materials, in particular silver dye bleach materials, can be prepared in a conventional manner known per se, which materials contain, on a base, at least one dye of the formula (1) dissolved in oil, in at least one silver halide emulsion layer or in a colloid layer adjacent to the silver halide emulsion layer.

The compounds of the formulae (1) to (10) dissolved in oil, show several advantages.

Thus, they are distinguished by the high stability of their emulsions. A tendency to form micelles is completely absent, so that there is no adverse influence on the colour density of the photographic images.

The oil acts not only as a solvent for dyes, but it can at the same time be a plasticiser for the gelatine. The possible detachment, which can occur especially under moist conditions, of the photographic layers from the material of the base is thus largely prevented.

As a result of the good solubility of the dyes in oil, a large capacity for taking dye in an oil droplet can be achieved. Thus, it is possible to coat photographic materials having very thin layers. This has an advantageous effect on the sharpness of the images.

As the base for the silver halide emulsion layers, a material can be used which is transparent, has a metallic reflection or preferably is white-opaque and which preferably is unable to absorb liquid from the baths.

For example, the base can consist of pigmented or unpigmented cellulose triacetate or polyester. If it consists of paper felt, the latter must, on both sides, be lacquered or coated with polyethylene. The light-sensitive layers are located on at least one side of this base, preferably in the known arrangement, i.e. a red-sensitised silver halide emulsion layer containing a cyan azo dye at the bottom, on top of this a green-sensitised silver halide emulsion layer containing a magenta azo dye and, at the top, a blue-sensitive silver halide emulsion layer containing a yellow azo dye. The material can also contain subbing layers, interlayers, filter layers and protective layers, but the total thickness of the layers should in general not exceed 20 μm.

The dyes according to the invention are lipophilic and are in general incorporated into the gelatine as solutions in high-boiling solvents. In most cases, it suffices to add the dyes, which are to be used, as a solution in such a solvent, if necessary with the aid of a highly volatile auxiliary solvent, at normal or slightly elevated temperature to an aqueous gelatine solution, with thorough stirring. Subsequently, the mixture and gelatine containing silver halide and/or materials for the production of photographic images are brought together, and the whole is coated on a base in the conventional manner to give a layer and, optionally, is dried.

Disazo dyes of the formula (1) dissolved in organic solvents can be added directly to a gelatine containing silver halide and/or other materials for the production of photographic images. It is thus possible, for example, that the dye solution is mixed in only just before coating.

In place of simple stirring, the conventional distribution methods by means of kneading forces and/or shear forces or ultrasonics can also be used.

It is also possible to add the dye not as a solution but in the solid form as a fine suspension. Furthermore, it is possible to incorporate the dyes into the gelatine in the presence of high-molecular polymers. Latices are of particular interest for this application.

The coating solution can also contain further additives, such as hardeners, complexing agents and wetting agents as well as sensitisers and stabilisers for the silver halide.

The disazo dyes do not undergo any chemical reactions with the light-sensitive materials. The dyes of the formula (1) are highly resistant to diffusion, since they form stable organic solutions. They are insensitive to calcium ions and can readily be bleached to white.

When added to the coating solutions, the disazo dyes do not cause any rise in viscosity or a significant change in viscosity, when the coating mixture is left to stand.

The spectral absorptions in gelatine are such that, depending on the structure, the dyes of the formula (1) can be combined to give a dye tripack which is assembled from one yellow dye, one magenta dye and one cyan dye and which, over the entire density range, has grey shades which appear neutral to the eye.

The photographic silver dye bleach material prepared using disazo dyes of the formula (1) is distinguished in particular by brilliant colours, good colour reproduction and excellent light fastness. An important feature of a good colour-copying material is optimum reproduction of shades and colour gradations which are balanced in all density ranges. Particularly the control of colour balance causes difficulties again and again, since the different behaviour of the azo dyes during bleaching cannot always be balanced by the conventional methods of assembling the material, such as matching the sensitivity and contrast of the silver halide emulsion used. In many cases, this restricts the selection of the image dyes and, in particular, also the selection of the processing components in the bleach bath.

The processing of the exposed silver dye bleach material is in general carried out in four successive steps:

1. Silver development

2. Dye bleaching

3. Silver bleaching

4. Fixing.

In the first step, the latent silver image produced during exposure is developed. In the second step, the image dye associated with the silver is bleached, corresponding to the actual imagewise distribution of the silver. The third step is necessary in order to reoxidise the excess image silver which is still present after the dye bleaching step. In the fourth step, the silver which is now present completely in the form of halides is removed by dissolving it out by means of a complexing agent, in particular a salt of thiosulfuric acid, in order to make the finished image insensitive to further exposure and to remove turbidity from the pure colour image.

In the conventional known processes, the second process step, namely dye bleaching, is carried out in a strongly acid medium, a catalyst being added in order to accelerate the dye bleaching. Additionally, the bleach baths contain a silver-complexing agent or a ligand. Both these constituents, the catalyst and the ligand, are necessary in order to transfer the reducing action of the metallic, non-diffusible image silver to the likewise non-diffusible dye. The reduced form of the catalyst, formed by reduction on the image silver, here functions as an intermediate carrier which, after covering a certain diffusion distance, irreversibly reduces and hence bleaches the dye and, at the same time, is itself reoxidised to the original form.

The property of the reduced stage of the bleach catalyst of freely diffusing between the image silver and the dye which is to be bleached enables the silver and the image dye to be spatially separated to a certain extent; in other words, the bleachable dye and the silver halide emulsion associated with it need not, or only partially, be located in the same layer and can, instead, be located in adjacent layers. Silver dye bleach materials of this type have been described, for example, in German Offenlegungsschriften Nos. 2,036,918, 2,132,835 and 2,132,836.

A simplification of the processing method, in which dye bleaching and silver bleaching are combined in a single process step, has been described in German Offenlegungsschrift No. 2,448,433.

The combined dye and silver bleach baths (formulations) for the processing of the exposed silver dye bleach material contain the components (a) to (e) and, if necessary, (f):

(a) strong acid,

(b) water-soluble iodide,

(c) water-soluble oxidising agent,

(d) an anti-oxidising agent,

(e) a bleach catalyst and

(f) a bleach accelerator.

The quantity of bleach catalysts used in the preferably aqueous treatment baths can vary within wide limits and is about 0.05 to 10 g/l of bleach bath.

The temperature of the bleach bath is in general between 20° and 90° C., preferably between 20° and 60° C., the required processing time at a higher temperature of course being shorter than that at a lower temperature. The bleach baths are stable within the temperature indicated. In general, the aqueous bleach formulations required for processing are used in the form of dilute aqueous solutions which contain the components mentioned. Other methods are, however, also conceivable, for example the use in the form of a paste.

This temperature range also applies to the other processing steps. The aqueous bleach formulation according to the present invention can be prepared, for example, from liquid, in particular aqueous concentrates of individual components or all the components ((a) to (f)). For example, two liquid concentrates are advantageously used, of which one contains strong acid (a) and the oxidising agent (c) and the other contains the remaining components (b), (d), (e) and, optionally (f); to improve the solubility, especially that of component (e), an additional solvent, such as ethyl alcohol or propyl alcohol, benzyl alcohol, ethylene glycol methyl ether or ethylene glycol ethyl ether, can be added to the latter concentrate. These concentrates (partial concentrates) which are also a subject of the present invention, have excellent stability and can therefore be stored for prolonged periods. These concentrates can be diluted as appropriate by dilution with water or with a mixture of water and an organic solvent and can be used in the process according to the invention. The aqueous bleach formulations used contain as a rule the following quantities of components (a) to (f):

(a) strong acid: 10 to 200 g/l,

(b) water-soluble iodide: 2 to 50 g/l, preferably 5 to 25 g/l,

(c) water-soluble oxidising agent: 1 to 30 g/l,

(d) anti-oxidising agent: 0.5 to 10 g/l,

(e) bleach catalysts: 0.05 to 10 g/l and, optionally

(f) bleach accelerator: 1 to 5 g/l.

The concentrates of the individual components or all the components or their combinations, for example of components (a) and (c) and of components (b), (d), (e) and (f) can contain, per liter of concentrated formulation 2 to 20 times, preferably 5 to 10 times, the quantity of the individual components, which was indicated above for the ready-to-use bleach baths. As a rule, the concentrates are in the form of a liquid or paste.

The strong acids (component (a)) contained in the combined dye bleach and silver bleach baths can be alkylsulfonic acids or arylsulfonic acids and, in particular, p-toluenesulfonic acid, sulfuric acid, sulfamic acid or trichloroacetic acid. It is also possible to use mixtures of these acids. The pH value of the bleach bath is in particular less than 2 and preferably less than 1.

The water-soluble iodides (component (b)) are as a rule alkali metal iodides, in particular sodium iodide and potassium iodide.

The oxidising agents (c) used are advantageously water-soluble aromatic mononitro compounds and dinitro compounds, or anthraquinonesulfonic acid derivatives. The use of such oxidising agents serves to influence the colour balance and the contrast of the images produced by the dye bleach process and is known from German Patent Specification No. 735,672, British Patent Specifications Nos. 539,190 and 539,509, and Japanese Patent Publication No. 22,673/69.

The mononitro and dinitro compounds preferably are mononitro- or dinitro-benzenesulfonic acids, for example those of the formula ##STR41## in which n is 1 or 2, and R and R' are hydrogen, lower alkyl having 1 to 4 carbon atoms, alkoxy, amino, hydroxyl or halogen (chlorine or bromine). The sulfonic acids can be added as the readily soluble salts. For example, the sodium or potassium salts of the following acids are suitable: o-nitrobenzenesulfonic acid, m-nitrobenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid, 3,5-dinitrobenzenesulfonic acid, 3-nitro-4-chlorobenzenesulfonic acid, 2-chloro-5-nitrobenzenesulfonic acid, 4-methyl-3,5-dinitrobenzenesulfonic acid, 3-chloro-2,5-dinitro-benzenesulfonic acid, 2-amino-4-nitrobenzenesulfonic acid, 2-amino-4-nitro-5-methoxybenzenesulfonic acid and 4-nitrophenyl-2-hydroxybenzenesulfonic acid.

In addition to their function as a silver bleaching agent, the compounds of component (c) also serve for lowering the gradation.

Advantageously, the anti-oxidising agents (anticorrosion agents) (d) used are reductones or water-soluble mercapto compounds. Suitable reductones are in particular aci-reductones having a 3-carbonyl-1,2-diol grouping, such as reductone, triose-reductone or preferably ascorbic acid. Examples of possible mercapto compounds are thioglycerol, in particular compounds of the formula

    HS--C.sub.q H.sub.2q --B or preferably                     (25)

    HS--(CH.sub.2).sub.m --COOH                                (26)

in which q is an integer having a value from 2 to 12, B is a sulfonic acid or carboxylic acid group and m is one of the numbers 3 and 4. Mercapto compounds which can be used as anti-oxidising agents are described in German Offenlegungsschriften Nos. 2,258,076 and 2,423,814. Further suitable anti-oxidising agents are the alkali metal, alkaline earth metal or ammonium bisulfite adducts of organic carbonyl compounds, preferably alkali metal or ammonium bisulfite adducts of monoaldehydes having 1 to 4 carbon atoms or dialdehydes having 2 to 5 carbon atoms (German Offenlegungsschrift No. 2,737,142).

Examples which may be mentioned are the formaldehyde-bisulfite adduct which is particularly preferred, and also the corresponding adducts of acetaldehyde, propionaldehyde, butyraldehyde or isobutyraldehyde, and those of glyoxal, malonic dialdehyde or glutaric dialdehyde. Optionally, the following tertiary water-soluble phosphines, termed bleach accelerators, can also be employed simultaneously as the anti-oxidising agents.

Examples of suitable bleach accelerators (f) are quaternary ammonium salts, such as those known from German Offenlegungsschriften Nos. 2,139,401 and 2,716,136. Preferably these are quaternary, substituted or unsubstituted piperidine, piperazine, pyrazine, quinoline or pyridine compounds, the latter being preferred. It is also possible to use tetraalkylammonium compounds (alkyl having 1 to 4 carbon atoms) and alkylenediammonium compounds (alkylene having 2 to 6 carbon atoms). Specific compounds are: tetraethylammonium iodide,

    (CH.sub.3).sub.3 N.sup.⊕ (CH.sub.2).sub.2 N.sup.⊕ (CH.sub.3).sub.3.2I.sup.⊖, (CH.sub.3).sub.3 N.sup.⊕ (CH.sub.2).sub.6 N.sup.⊕ (CH.sub.3).sub.3.2I.sup.⊖,

N-methylpyridinium iodide, N-methylquinolinium iodide, N-hydroxyethylpyridinium chloride, N-hydroxypropylpyridinium bromide, N-methyl-2-hydroxymethylpyridinium iodide, N,N-dimethylpiperidinium iodide, N,N'-dimethylpyrazinium fluorosulfate and γ-picolinium bisulfate.

Further bleach accelerators are the water-soluble tertiary phosphines which are known from German Offenlegungsschrift No. 2,651,969 and which preferably contain at least one cyanoethyl grouping.

They are, for example, of the formula ##STR42## in which W is --C_(r) H_(2r) CN, --C_(r) H_(2r) NO₂, a substituted or unsubstututed aryl radical or a heterocyclic radical, r is 1 to 25, X is substituted or unsubstituted alkyl and Y is hydroxyalkyl, alkoxyalkyl, sulfoalkyl, aminoalkyl (alkyl in each case having 1 to 25, preferably 2 to 4, carbon atoms), phenyl, sulfophenyl or pyridyl. Preferred tertiary phosphines are of the formula ##STR43## in which X₁ is --CH₂ CH₂ CN or --(CH₂)₂ OCH₃, Y₁ is --(CH₂)₂ SO₃.sup.⊖ M.sup.⊕, --(CH₂)₃ --SO₃.sup.⊕ M.sup.⊖, --(CH₂)₄ --SO₃.sup.⊖ M.sup.⊕, --(CH₂)₂ OCH₃ or --CH₂ N(C₂ H₅)₂, W₁ is --CH₂ CH₂ CN or phenyl and M⁺ is a cation, in particular an alkali metal cation, for example the sodium or potassium cation.

Specific compounds are the following: bis-(β-cyanoethyl)-2-sulfoethylphosphine (sodium salt), bis-(β-cyanoethyl)-3-sulfopropylphosphine (sodium salt), bis-(β-cyanoethyl)-4-sulfobutylphosphine (sodium salt), bis-(β-cyanoethyl)-2-methoxyethylphosphine, bis-(2-methoxyethyl)-(β-cyanoethyl)-phosphine, (β-cyanoethyl)-phenyl-3-sulfopropylphosphine (sodium salt), (β-cyanoethyl)-phenyl-2-methoxyethylphosphine and bis-(2-methoxyethyl)-phenylphosphine.

A repeat of individual treatments (each time in a further tank with a bath having the same composition as the preceding bath) is possible; in some cases, better bath utilisation can be achieved in this way. If permitted by the number of available tanks and by the time programme, water baths can also be inserted between baths having different actions. It is up to the expert to determine the optimum quantity from the sensitometric results, depending on the type of catalysts selected. All the baths can contain further conventional additives, for example hardeners, wetting agents, fluorescent brighteners or UV stabilisers.

Baths of conventional composition can be used for the silver development, for example those which, as the developer substance, contain hydroquinone and, optionally, additionally 1-phenyl-3-pyrazolidinone. In some cases, the silver developing bath already contains a bleach catalyst.

The silver fixing bath can have the known and conventional composition. The fixer used is, for example, sodium thiosulfate or, with advantage, ammonium thiosulfate, optionally with additions such as sodium bisulfite and/or sodium metabisulfite.

EXAMPLE 1 Preparation of the dye of the formula ##STR44## 1.25 g (0.005 mol) of 4,4'-diamino-diphenylsulfone are dissolved in 75 ml of water in the presence of 3.6 g of concentrated hydrochloric acid. A solution of 0.72 g (10.5 mmols) of sodium nitrite in 10 ml of water is added dropwise at 5° C. The solution is stirred for one hour at 5° C. The resulting solution of the diazonium salt is added, at 5° C., to a mixture of 1.64 g (0.01 mol) of p-tert.-amylphenol and a solution of 4.25 g of sodium carbonate in 250 ml of 65% ethanol. The mixture is stirred for 2 hours, and the precipitate is filtered off with suction. After purification by chromatography on silica gel with chloroform (99 parts) and ethyl acetate (1 part), this gives 2 g (67%) of the yellow dye having a melting point of 165° to 167° C. λ_(max) ^(CH).sbsp.3^(Cl).sbsp.3 =423 nm, λ_(max) ^(gelatine) =419 nm. EXAMPLE 2 Preparation of the dye of the formula ##STR45## (a) Diazo component (a₁) Bis-4,4'-acetamido-diphenylmethane

109.5 g (0.55 mol) of 4,4-diamino-diphenylmethane are dissolved in 800 ml of toluene. 112.3 g (1.10 mols) of acetic anhydride are added to this solution. The resulting suspension is boiled under reflux for 4 hours. The mixture is then allowed to cool, and the precipitate is filtered off with suction and dried at 70° C. in vacuo. The yield is 146 g (90%) and the melting point is 225° to 226° C.

(a₂) Bis-4,4'-acetamido-benzophenone

28.0 g (0.10 mol) of bis-4,4'-acetamido-diphenylmethane are suspended in 250 ml of acetic acid. 27.5 g (0.26 mol) of CrO₃ are added in portions at 60° C. The mixture is stirred for 2 hours at this temperature and for a further 2 hours at 90° C. The resulting solution is poured into 3 l of ice-water. The precipitate formed is filtered off with suction and washed with water. The crude product is dissolved in 100 ml of acetone. After insoluble fractions have been separated off, the solution is stirred into 500 ml of water. The precipitate formed is filtered with suction and dried at 70° C. in vacuo. The yield is 20.0 g (67.5%), and the melting point is 230° to 232° C.

(a₃)4,4'-Diamino-benzophenone

15.0 g (0.05 mol) of bis-4,4'-acetamido-benzophenone are boiled under reflux for 3 hours in 75 g of concentrated hydrochloric acid and 75 g of water. The mixture is diluted with 500 ml of water and neutralised with 30% sodium hydroxide solution. The precipitate formed is filtered off with suction, washed with water and dried at 60° C. in vacuo. The yield is 10.0 g (93%), and the melting point is 238° to 240° C.

(a₄) 4,4'-Diamino-2,2',6,6'-tetrabromo-benzophenone

2.12 g (0.01 mol) of 4,4'-diamino-benzophenone are suspended in 100 ml of 2-methoxyethanol in the presence of 3 g of concentrated hydrochloric acid. A solution of 12 g (0.075 mol) of bromine, 2 g of sodium bromide and 20 ml of methanol is added dropwise. The reaction mixture is stirred for 2 hours and then poured into 300 ml of water. The excess bromine is destroyed by adding sodium sulfite. The precipitate formed is filtered off with suction, washed with water and then with methanol, and dried at 60° C. in vacuo. The yield is 4.8 g (90%), and the melting point is 241° to 243° C. (decomposition).

(b) Coupling component Preparation of 2-methoxy-5-isovalerylamido-N,N-dibutylaniline

13.35 g (0.06 mol) of 2-amino-4-isovalerylamidoanisole are dissolved under nitrogen in 200 ml of N,N-dimethylacetamide. 10 g (0.25 mol) of magnesium oxide and 27.4 g (0.2 mol) of butyl bromide are added. The mixture is heated at 130° C. for six hours and finally cooled down. The suspension is filtered with suction, and the filtrate is poured into 100 ml of ice-water. The precipitate is filtered off with suction, and the crude product is recrystallised from 40 ml of acetonitrile in the presence of animal charcoal. This gives 16.0 g (80%) of 2-methoxy-5-isovalerylamido-N,N-dibutylaniline having a melting point of 88° to 90° C.

The nuclear magnetic resonance spectrum (in CDCl₃) and the elementary analysis confirm the chemical structure of the coupling component.

(c) Preparation of the azo dye of the formula ##STR46##

0.30 g of methanesulfonic acid and then 0.22 g of nitrosylsulfuric acid are added to 0.37 g (0.7 mmol) of 4,4'-diamino-2,2',6,6'-tetrabromo-benzophenone in 25 ml of acetic acid. After stirring for 90 minutes at room temperature, the diazonium suspension is introduced into a mixture of 0.5 g of 2-methoxy-5-isovalerylamido-N,N-dibutylaniline, 30 ml of N,N-dimethylformamide, 30 ml of acetic acid and 1.0 g of sodium acetate. The reaction mixture is stirred for two hours at 15° C. and poured into 150 ml of ice-water. The precipitate is filtered off with suction, dissolved in chloroform and dried over magnesium sulfate. After evaporation of the solvent, the oily residue is eluted from silica gel with a mixture of chloroform (97 parts) and hexane (1 part). The yield of magenta dye is 0.37 g (43%) λ_(max) ^(CHCl).sbsp.3 =532 nm (ε=44,700).

(d) Preparation of the azo dye of the formula ##STR47##

0.1 g of copper(I) cyanide and 0.7 g of zinc cyanide are added to 0.45 g (0.37 mmol) of the dye, prepared under (c), in 30 ml of N-methylpyrrolidone. The mixture is stirred for 20 hours at 120° C. and introduced into 50 ml of 10% sodium chloride solution. The precipitate is filtered off with suction, washed with water and dried. The residue is eluted from silica gel with a mixture of hexane (8 parts) and pyridine (2 parts). The yield of cyan dye is 0.15 g (40%). λ_(max) ^(CHCl).sbsp.3 =677 nm (ε=154,000) λ_(max) ^(gelatine) =634 nm. The dyes are listed in Table 3 are prepared in an analogous manner.

    TABLE 3       X.sub.1 Y.sub.1 Z.sub.1 R.sub.1 R.sub.2 W.sub.1 R.sub.3 R.sub.4      λ.sup.CHCl.sbsp.3.sub.max ε.sub.mol λ.sup.Gel..sub.m      ax        101 NHCOCH.sub.2 CH(CH.sub.3).sub.2 N(C.sub.4 H.sub.9).sub.2 OCH.sub.3 H       H H H CHCH 551 83,200 552 102 " " OCH.sub.3 Br Br H H SO.sub.2 528      49,800 545 103 " " OCH.sub.3 CN CN H H SO.sub.2 675 14,6000  615 104 " "      OCH.sub.3 CN CN H H CO 677 15,4000  634 105 " N(CH.sub.3).sub.2 H H H H      H SO.sub.2 499 76,800 478  106 NHPO(OC.sub.2       H.sub.5).sub.2      ##STR48##       OCH.sub.3 CN CN H CH.sub.3 CH.sub.2 CH.sub.2 575 93,800 588   107      NHPO(OC.sub.4 H.sub.9).sub.2 NHC.sub.2 H.sub.4 CN H Br Br H CH.sub.3      CH.sub.2 CH.sub.2 394 46,700 400  108 NHPO(OC.sub.4 H.sub.9).sub.2       ##STR49##       OCH.sub.3 CN CN H CH.sub.3 CH.sub.2 CH.sub.2 573 87,700 594  109 "      N(C.sub.2 H.sub.5).sub.2 OCH.sub.3 CN CN H H SO.sub.2 639 120,000  630      110 " N(C.sub.2 H.sub.5).sub.2 OCH.sub.3 CN CN H HCO 626 96,300 625 111      " N(C.sub.2 H.sub.5).sub.2 OCH.sub.3 CN CN H H -- 662 95,000 640 112      NHCOCH.sub.2 (CH.sub.3).sub.2 N(C.sub.4 H.sub.9).sub.2 OCH.sub.3 CN      NO.sub.2 H H SO.sub.2 638 136,000  630 113 " N(C.sub.4 H.sub.9).sub.2      OCH.sub.3 Br Br H H -- 526 58,200 543 114 " N(C.sub.4 H.sub.9).sub.2      OCH.sub.3 CN CN H H -- 679 157,000  625       115 OH H      ##STR50##       H H H H O 413 17,100 439       116 OH H      ##STR51##       H H H H O 403 26,700 399  117 OH H " H H H H CHCH 456 43,100 460  118      OH H       ##STR52##       H H H H CHCH 450 53,800 440  119 OH H CH.sub.2 CO.sub.2 (C.sub.2      H.sub.4 O).sub.2 CH.sub.3 H H H H SO.sub.2 413 18,100 403 120 OH H      O(C.sub.2 H.sub.4 O).sub.2 CH.sub.3 H H H H SO.sub.2 467 14,900 445 121      OH H " H H H H O 439 18,700 442 122 OH H O(C.sub.2 H.sub.4 O).sub.2      CH.sub.3 H H H H CO 464 17,100 465 123 OH H OCH.sub.2 CH(CH.sub.3).sub.2      H H H H SO.sub.2  473 15,200 462 124 OH H " H H H H O 445 16,200 445 125      OH H C(CH.sub.3).sub.2 CH.sub.2 CH.sub.3 H H H H SO.sub.2 423 17,500 419      126 OH H " H H H H CO 417 19,100 415 127 OH H " H H H H CHCH 456 52,100      435 128 OH OCH.sub.2 CH.sub.2 CH(CH.sub.3).sub.2 CH.sub.3 H H H H O 430      40,800 420 129 OH OC.sub.2 H.sub.4 OC.sub.4 H.sub.9 CH.sub.3 H H H H O      425 37,200 420 130 OH OC.sub.2 H.sub.4 OC.sub.2 H.sub.4 OCH.sub.3      CH.sub.3 H H H H O 425 38,200 432 131 OH OCH.sub.3 NHCOCH.sub.2       CH(CH.sub.3).sub.2 H H H H O 443 32,400 430 132 OH OC.sub.3 H.sub.7      CH.sub.3 H H H H SO.sub.2 455 36,700 401 133 OH OC.sub.3 H.sub.7      CH.sub.3 H H H H O 433 38,500 425 134 OH H CH.sub.2 CO.sub.2 CH.sub.2      CH(CH.sub.3).sub.2 H H H H SO.sub.2 412 18,800 405 135 OH H C(CH.sub.3).s      ub.3 H H CH.sub.3 H SO.sub.2 435 13,300 430  136 NHCOC.sub.2 H.sub.5       ##STR53##       OC.sub.2 H.sub.4 OCH.sub.3 H H H H CO 525 54,400 526  137 NHCOC.sub.2      H.sub.5       ##STR54##       OC.sub.2 H.sub.4 OCH.sub.3 Br H H H SO.sub.2 541 39,400 539  138      NHCOC.sub.2       H.sub.5      ##STR55##       OC.sub.2 H.sub.4 OCH.sub.3 Br H H H CO 543 53,800 545  139 NHCO.sub.2      H.sub.5       ##STR56##       OC.sub.2 H.sub.4 OCH.sub.3 Cl H H H SO.sub.2 547 48,100 544  140      NHCOC.sub.2 H.sub.5 N(C.sub.2 H.sub.5).sub.2 OC.sub.2 H.sub.4 OCH.sub.3      H H H H SO.sub.2 538 44,800 536 141 NHCOCH.sub.2 CH(CH.sub.3).sub.2      N(C.sub.2 H.sub.5).sub.2 OC.sub.2 H.sub.4 OCH.sub.3 H H H H CO 574      42,600 539 142 NHCOCH.sub.2 CH(CH.sub.3).sub.2 NHC.sub.4 H.sub.9      OCH.sub.3 H H H H CO 532 58,500 527 143 NHCOCH.sub.2 CH(CH.sub.3).sub.2      NHC.sub.4 H.sub.9 OCH.sub.3 Br H H H SO.sub.2 549 41,900 557  144      NHPO(OC.sub.2       H.sub.5).sub.2      ##STR57##       OCH.sub.3 H H H H CHCH 534 64,200 539  145 NHPO(OC.sub.2 H.sub.5).sub.2       ##STR58##       OCH.sub.3 Br H H H SO.sub.2 549 66,000 --  146 NHPO(OC.sub.4       H.sub.9).sub.2 N(C.sub.2 H.sub.5).sub.2 OCH.sub.3 H H H H SO.sub.2 522      44,300 526 147 NHPO(OC.sub.2 H.sub.5).sub.2 NHCHCH.sub.2       CH(CH.sub.3).sub.2 OCH.sub.3 H H H H CO 521 48,700 526       48 NHPO(OC.sub.2       H.sub.5 ).sub.2      ##STR59##       OCH.sub.3 H H H       ##STR60##       -- 532 50,100 537/564  149 NHPO(OC.sub.2       H.sub.5).sub.2      ##STR61##       OCH.sub.3 H H H       ##STR62##       -- 550 37,900 554

EXAMPLE 3

20.2 mg of the dye of the formula ##STR63## are dissolved in 2 ml of a mixture of ethyl acetate and tricresyl phosphate (mixing ratio 9:1) and the solution is added to a mixture of 6.6 ml of 6% aqueous gelatine solution, 0.9 ml of distilled water and 0.5 ml of an 8% solution of the sodium salt of dibutylnaphthalenesulfonic acid, and the mixture is emulsified by means of ultrasonics.

2.5 ml of the emulsion obtained are mixed with 5 ml of water, 1.5 ml of a non-sensitised gelatine silver bromide/iodide emulsion which contains about 22 g of silver/kg of gelatine, 1 ml of 4% gelatine solution and 1 ml of a 1% solution of a hardener of the formula ##STR64## This mixture is coated onto an opaque triacetate base (13×18 cm size) and dried. The light-sensitive material thus obtained is exposed behind a step wedge and processed at 24° C. as follows:

    ______________________________________                                         Developing            6     minutes                                            Washing               4     "                                                  Silver and dye bleach 6     "                                                  Washing               2     "                                                  Fixing                8     "                                                  Washing               6     "                                                  Drying.                                                                        ______________________________________                                    

The developing and fixing baths are conventional baths, as used in black-and-white photography. The silver dye bleach bath has the following composition, per liter of solution:

    ______________________________________                                         Sulfamic acid           100    g                                               m-Nitrobenzenesulfonic acid                                                                            10     g                                               Potassium iodide        6      g                                               2,3,6-Trimethylquinoxaline                                                                             2      g                                               4-Mercaptobutyric acid  1      g                                               ______________________________________                                    

This gives a counter-imagewise yellow wedge which is bleached completely white in the area of the originally highest silver density. The image is distinguished by high brillance and light fastness.

EXAMPLE 4

11.4 mg of the dye of the formula ##STR65## are dissolved in 2 ml of a mixture (mixing ratio 9:1) of ethyl acetate and tricresyl phosphate.

This mixture is emulsified with 7 ml of 5% gelatine solution and 0.5 ml of 8% aqueous solution of the sodium salt of dibutylnaphthalenesulfonic acid to give a homogeneous mixture. 5 ml of water, 0.5 ml of a non-sensitised gelatine silver bromide emulsion which contains about 22 g of silver per kg of gelatine, 2.0 ml of 4% gelatine solution and 1 ml of 1% hardener solution are added to 2.5 ml of this dye emulsion. This mixture is coated onto a 13×18 cm opaque triacetate sheet and dried. The light-sensitive material thus obtained is exposed with white light behind a step wedge and processed at 30° C. as follows:

    ______________________________________                                         Developing            3     minutes                                            Washing               1     "                                                  Silver and dye bleaching                                                                             5     "                                                  Washing               1     "                                                  Fixing                4     "                                                  Washing               6     "                                                  Drying.                                                                        ______________________________________                                    

The developer bath has the following composition, per liter of solution:

    ______________________________________                                         Sodium sulfate          50    g                                                1-Phenyl-3-pyrazolidone 0.2   g                                                Hydroquinone            6     g                                                Sodium carbonate        35    g                                                Potassium bromide       4     g                                                Benzotriazole           0.3   g.                                               ______________________________________                                    

The silver dye bleach bath has the following composition, per liter of solution:

    ______________________________________                                         Concentrated sulfuric acid                                                                              28    ml                                              m-Nitrobenzenesulfonic acid                                                                             10    g                                               (sodium salt)                                                                  Potassium iodide         6     g                                               Bis-(2-cyanoethyl)-(2-sulfoethyl)-                                                                      3     g                                               phosphine (sodium salt)                                                        2,3-Dimethylquinoxaline  1.5   g.                                              ______________________________________                                    

The fixing bath contains, per liter of solution:

    ______________________________________                                         Sodium thiosulfate     200    g                                                Sodium metabisulfite   20     g.                                               ______________________________________                                    

This gives a brilliant, light-fast cyan wedge which is bleached completely white in the areas of the originally highest silver density. 

What is claimed is:
 1. A compound of the formula ##STR66## in which X₄ is --NHCOM₁₂ or --NHP(O)(OG₁₂)₂, in which M₁₂ is alkyl having 1 to 16 carbon atoms, which is unsubstituted or substituted by carbalkoxy having 2 to 5 carbon atoms or by methoxy or ethoxy, and in which G₁₂ is alkyl having 1 to 4 carbon atoms, or X₄ is hydroxyl, Z₄ is hydrogen, alkyl or alkoxy having 1 to 8 carbon atoms or --CH₂ CO₂ R₅₃, in which R₅₃ is alkyl having 1 to 4 carbon atoms, --C₂ H₄ O)₂ --CH₃ or --C₂ H₄ O--CH₃, or Z₄ is --(OC₂ H₄)n₂ --OU₁₂ or --NL₂₁ COM₃₂, in which U₁₂ is hydrogen or alkyl having 1 to 4 carbon atoms, n₂ is 1 or 2, L 21 is hydrogen or alkyl having 1 to 4 carbon atoms and M₃₂ is alkyl having 1 to 8 carbon atoms, R₃₃ is hydrogen or methyl or, if R₄₂ is a direct chemical bond, the two radicals R₃₃ are hydrogen or methyl or form together a link member of the formula --CH₂ -- or --CO--, W₂ is hydrogen or methyl, Y₃ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy, acetoxy, hydroxyl or cyano, or Y₃ is --NHCOM₂₂, in which M₂₂ is alkyl having 1 to 4 carbon atoms, methoxy or --O--(C₂ H₄ O)--n₂ --CH₃, in which n₂ is 1 or 2, R₁₂ and R₂₂ independently of one another are hydrogen, chlorine, bromine, cyano, nitro or methylsulfone, R₄₂ is a direct chemical bond, or a link member of the formula --O--, --CO--, --SO₂ --, --(CH₂)m₂ --, in which m₂ is an integer from 1 to 6, or --CH═CH-- , and at least one of the substituents W₂, Y₃ and Z₄ is other than hydrogen, and X₄ L is different from hydroxyl, if Z₄ is hydrogen, and Z₄ is different from methyl, tert.-butyl and 1-hexyl, if R₄₂ is the direct chemical bond, --O--, --CH₂ -- or --CH═CH--, or the compounds of the formula ##STR67## wherein Y' is --OC₂ H₄ CH(CH₃)₂, OC₂ H₄ OC₄ H₉, --(OC₂ H₄)₂ OCH₃ or --OC₃ H₇.
 2. A compound according to claim 1, of the formula ##STR68## in which X₅ is --NHCOM₁₃, in which M₃ is alkyl having 1 to 16 carbon atoms, or --NHP(O)(OG₁₂)₂, in which G₁₂ is as defined above, or is hydroxyl, Y₄ is hydrogen, alkoxy having 1 to 8 carbon atoms or --OC₂ H₄)_(n).sbsb.2 --OU₁₃, in which U₁₃ is methyl or ethyl and n₂ is as defined above, or Y₄ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy, hydroxyl or cyano, Z₅ is hydrogen, alkyl or alkoxy having 1 to 5 carbon atoms or --CH₂ CO₂ R₅₃, in which R₅₃ is as defined above, or Z₅ is --OC₂ H₄)₂ --OCH₃, --OC₂ H₄)₂ --OH, --OC₂ H₄ --OH, --OC₂ H.sub. 4 --OCH₃ or --N(CH₃)COM₃₂, in which M₃₂ is as defined above, R₁₃ and R₂₃ independently of one another are hydrogen, chlorine, bromine, cyano, nitro or methylsulfone, R₃₄ is hydrogen or methyl or, if R₄₂ is a direct chemical bond, the two radicals R₃₄ are hydrogen or methyl or together form a link member of the formula --CH₂ -- or --CO--, and W₂ and R₄₂ are as defined above, and at least one of the substituents W₂, Y₄ and Z₅ is other than hydrogen, and X₅ is different from hydroxyl, if Z₅ is hydrogen, and Z₅ is different from methyl or tert.-butyl, if R₄₂ is the direct chemical bond, --O--, --CH₂ -- or --CH═CH--, or the compounds of the formula (100).
 3. A compound according to claim 2, of the formula ##STR69## in which X₆ is --NHCOM₁₃ or --NHP(O)(OG₁₂)₂, in which M₁₃ and G₁₂ are as defined above, Y₅ is N-alkylsubstituted or N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy or ethoxy, Z₆ is hydrogen, alkyl having 1 to 5 carbon atoms, --OC₂ H₄)₂ --OCH₃, --OC₂ H₄)₂ --OH, --OC₂ H₄ OCH₃ or --OC₂ H₄ --OH, R₁₄ and R₂₄ independently of one another are hydrogen, chlorine or bromine, R₃₅ is hydrogen or, if R₄₃ is a direct chemical bond, the two radicals R₃₅ are hydrogen or form together a link member of the formula --CH₂ -- or --CO--, and R₄₃ is a direct chemical bond or a link member of the formula --CO--, --SO₂ -- or --CH═CH-- , and X₆ is different from hydroxyl, if Z₆ is hydrogen, and Z₆ is different from methyl or tert.-butyl, if R₄₃ is the direct chemical bond or --CH═CH--, or the compounds of the formula (100).
 4. A compound according to claim 2, of the formula ##STR70## in which Y₆ is N,N-dialkylsubstituted amino, the alkyl moieties each containing 1 to 8 carbon atoms and being unsubstituted or substituted by methoxy, ethoxy or cyano, R₁₅ and R₂₄ independently of one another are cyano, nitro or methylsulfone, R₄₄ is a direct chemical bond or a link member of the formula --CO-- or --SO₂ -- and X₆ and Z₆ are as defined above, and X₆ is different from hydroxyl, if Z₆ is hydrogen, and Z₆ is different from methyl or tert.-butyl, if R₄₃ is the direct chemical bond or --CH═CH--, or the compounds of the formula (100). 